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WEB-BASED SPATIAL INFORMATION MANAGEMENT SYSTEMS
M. Bertolotto1, J.D. Carswell2, L. McGeown3, J. McMahon3,
1
Department of Computer Science, University College Dublin, Ireland, michela.bertolotto@ucd.ie
Digital Media Centre, Dublin Institute of Technology, Ireland, jcarswell@dit.ie
3
e-Spatial Solutions, Dublin, Ireland, info@e-spatialsolutions.com
2
ABSTRACT
In this paper we discuss the innovative software solutions offered by e-SpatialTM technology for the deployment of webbased and mobile spatial information management systems. This technology has been developed within the Oracle 9i
Database environment and allows users to build and deploy spatially enabled Internet applications on any Oracle
supported hardware platform and on any device running a Java Virtual Machine (e.g., standard web browsers, PDAs and
other mobile devices). The paper focuses on a Land Information Management System (LIMS) application developed for
the Irish Department of Agriculture. The application utilises the e-SpatialTM Information Server to deliver a spatially
enabled Internet solution for the tracking and management of land information based on land usage, land classifications
and land ownership changes over time. The developed land information management system provides a seamless Oracle 9i
Spatial database environment for the combination of multiple land information datasets. Integrated database topology
ensures the integrity of the topology relationships within the spatial database. The normal edit (e.g. create, modify, and
delete) and spatial analysis functions associated with a traditional GIS based land management applications, are deployed
as Java stored procedures in the Oracle Spatial database.
KEYWORDS: Web-based GIS; Land information management systems; Location-based services.
1. Introduction
To date users wishing to utilize commercial (web-based) GIS applications (such as Arcview/ArcInfo and ArcIMS;
MapInfo and MapInfo MapXtreme, Intergraph GeoMedia WebMap, etc.) in connection with their Oracle database, are
required to use proprietary application-specific software. In this paper we discuss the architectural issues of e-SpatialTM
technology, a timely alternative to traditional proprietary GIS packages for Oracle users (Bertolotto et al., 2001). Such
technology comprises a software solution for deploying web-based spatial applications within an Oracle 9i Database
environment that fully exploits the complete integration of spatial and non-spatial data repositories offered by Oracle
Spatial. e-SpatialTM technology extends the functionality of an Oracle Spatial database by providing a wide range of
advanced spatial data handling and management functions (e.g., real-time data display, collecting, manipulating, querying,
etc. using standard web browsers) typically provided by specialised GIS packages, without requiring any proprietary
application-specific source code.
These functions together with all data are stored in the enterprise database and can be accessed from any PC or mobile
device using functionality built into the database itself. Indeed, one of the greatest advantages of this software is that it is
seamlessly integrated into the database instead of being developed as a separate application. This has been achieved by
implementing all management information and spatial analysis functions as stored procedures. This characteristic makes
the package specifically suited for interactive real-time analysis and decision making in applications such as utility and
government mapping, navigation systems, GPS applications and the emerging mobile location-based applications.
The two main components of this technology are the iSMARTTM application development technology and the i-SpatialTM
Information Server (iSIS), both implemented within an Oracle 9i Spatial database environment. iSMARTTM is an intelligent
Oracle application database development technology that allows database administrators and software engineers to design,
build and deploy spatially enabled Internet applications without requiring any proprietary or application specific source
code. iSIS is a Java plug-in component of iSMARTTM. It consists of a database management application program that
exploits the spatial functionality inherent to an Oracle Spatial database.
In this paper we show the potentiality and performance of e-SpatialTM technology by describing a working system that
deploys it. The Land Information Management System (LIMS) application, developed for the Irish Department of
Symposium on Geospatial Theory, Processing and Applications,
Symposium sur la théorie, les traitements et les applications des données Géospatiales, Ottawa 2002
Agriculture, utilises the Spatial Information Server platform to deliver a spatially enabled Internet solution for the tracking
and management of land information based on land usage, land classification and land ownership changes over time.
The developed system provides a seamless Oracle 9i Spatial database environment for the combination of multiple land
information datasets. Integrated database topology ensures the integrity of the topology relationships within the spatial
database. The normal editing and spatial analysis functionality associated with traditional GIS based land management
applications are included, for example:
•
Vector data manipulation (pan, scroll, zoom, locate, window queries, etc.);
•
Vector and attribute data entry and editing;
•
Spatial and attribute data analysis (polygon overlay and network tracing);
•
Thematic mapping (display of query results with assigned symbology);
•
Raster/Vector integration.
This system allows for a wide variety of spatial analysis functionality and therefore provides an effective decision making
tool.
The remainder of this paper is organized as follows. Section 2 gives a brief overview of e-SpatialTM technology. Section 3
describes in detail the functionality of the land information management system that has been developed for the Irish
Department of Agriculture, while Section 4 presents some operational results of this system. Finally, Section 5 discusses
our concluding remarks and further issues that are currently under investigation.
2. e-SpatialTM technology
The two major components of e-SpatialTM technology architecture are the iSMARTTM database development technology
and the i-SpatialTM Information Server (iSIS) (Bertolotto et al. 2001). iSMARTTM is an intelligent Oracle application
database development technology that allows database administrators and software engineers to design, build and deploy
spatially enabled (as well as standard) Internet applications without requiring any proprietary or application specific source
code. It therefore allows to reduce overall system development and deployment costs. All iSMARTTM applications are
automatically generated on-the-fly directly from the Oracle database and can be used and modified on-line without having
to log-off existing Internet applications or writing any client application code. The iSMARTTM architecture is illustrated in
Figure 1.
Client Layer
iSMART Java
Applet
HTTP/RMI
Web Server
Application Server Layer
(Oracle 9iAS)
Database Layer
(Oracle 9i)
Figure 1. The three iSMARTTM architecture components: client layer, application server layer and database layer.
The application server currently used by iSMARTTM is Oracle 9iAS. This layer contains several Enterprise Java Beans
(EJBs) responsible for communication with the client layer and for querying the database layer tables. The structure of a
user application developed using iSMARTTM is stored in the form of a hierarchy of objects and panels (corresponding to
buttons, textfields, etc. and forms to be displayed on the user’s screen) in the Application Specific Metadata tables. Panel
(entity) EJBs are responsible for retrieval of such information.
The i-SpatialTM Information Server consists of a database management application program that enhances the spatial
functionality of an Oracle Spatial database. More details about the e-SpatialTM architecture can be found in (Bertolotto et
al., 2001).
Client Layer
SIS Viewer
Java Bean
Application Server Layer
Dispatcher 1
Session EJB
Dispatcher 2
Dispatcher …
Source B
Source A (Entity EJB)
Sector 1
Entity EJB
Sector 2
Entity EJB
Sector …
Entity EJB
Features
Entity EJB
Spatial Topology
Network Tracing
Java 1.2 based classes
PL/SQL Wrappers
Topology maintenance
Area generation
Connectivity model
Java 1.2 based classes
PL/SQL Wrappers
Shortest path trace
Custom trace support
User extendable
Smart Symbols
SI – Server Metadata
Symbol definitions
Instance definitions
Oracle 9i Database Layer
Figure 6. The iSIS architecture components: the client layer, the application server layer and the database layer.
The spatial data model used by e-SpatialTM technology is the Oracle Spatial object-relational model. The main advantage
provided by this model is the automatic reconstruction of topological properties upon update : if a spatial element is
updated (for example, by a remote user accessing the application web site in the field), all spatially related elements are
automatically changed accordingly to guarantee consistency. More details about the advantages of this approach can be
found in (Bertolotto et al., 2002).
Finally, another advantage of e-SpatialTM technology is the ease of use of its application development environment. In order
to facilitate current users of GIS applications that have been integrated in the widest range of information systems, e-
SpatialTM technology also provides a user-friendly environment that allows building and customising the application by
means of drag-and-drop functionality to add objects, such as buttons, textfields, tables, combo boxes, etc. to panels and subpanels in a hierarchical fashion (see (Bertolotto et al., 2001) for more details). In this way, even non-expert users can easily
build their own spatially enabled application. Additional development tools include: the Pyramid Builder, a utility designed
to load scanned aerial/satellite photos and topographic maps into the database; the Feature Builder, a utility that allows
users to define new data sources and the feature classes that the source controls; and Visuali, a tool specifically designed to
allow any user to build a customised graphic user interface for both standard management information systems and spatial
applications without writing any source code.
3. A land information management system
In this section the Land Information Management System (LIMS) implemented using e-SpatialTM technology is described.
The LIMS application, developed for the Irish Department of Agriculture, is a web-based spatial information system that
serves 125,000 farmers in the territory of the Republic of Ireland. A functional overview is provided in the following.
The functionality provided by the LIMS system include:
•
View farmers’ details online
•
Locate a parcel/area using different criteria
•
Digitising
•
Spatial queries
•
Printing
Accessing the system requires all users to logon with a valid name and password. Different security restrictions are applied
to different groups of users (e.g., only viewing/querying, viewing and editing, etc.).
In the following we describe how the system is used after authorised logon. At first the user is prompted with a homepage
from which several different options can be chosen. For example, the Farmer/Locate screen can be entered to view farmer
details and locate parcels (Figures 3 and 4). A remote user can view the claimant’s details to retrieve associated
information. To access details the user is required to enter a herd number and select a year from a drop-down list (Figure 3).
Farmer
panel
Figure 3. Screenshot of the Farmer panel.
By clicking on the locate button (Figure 4) it is possible to locate a parcel/area using several different criteria: cadastral
locate (specifying a county), Ordnance Survey locate (entering map numbers), coordinate locate (enter x and y map
coordinates), LPIS number (land parcel ID).
Locate
panel
Figure 4. Locate panel: example of locate functionality using the cadastral details.
Alternatively, the user could enter a herd number and a year to display all parcels where the specified herd is located. One
specific parcel can then be selected and viewed (Figure 5).
Figure 5. Alternative locate method: the user enters a herd number and year; then clicks on the Digitising tab (Parcel Data
will have been populated with plot and parcel data for the chosen herd number); the specific parcel is then selected and
viewed by right clicking on it and choosing the View Current Row option.
The on-line digitising functionality is accessible directly from the result screen of the locate search described above by
clicking the digitising tab (see Figure 6).
Digitising
panel
Digitising
tools
Figure 6. Digitising panel: besides viewing parcel data and changing visualisation settings, the user can utilise standard
digitising and validation tools.
Once the user has digitised a new parcel boundary, topology updating algorithms are automatically invoked within the
Oracle 9i Spatial database. Immediate printing capabilities of graphical/attribute editing updates represent additional
benefits of the system.
Spatial query functionalities of the system include: retrieving parcels of a given shape, area, centroid coordinates; buffer
queries; window queries; topological queries (e.g., based on overlapping, containment, etc.). Thematic queries are also
allowed where re-symbolisation of an area on a map is based on its attributes. In Figure 7 the Spatial Query panel is
illustrated.
To enable printing capabilities the Print tab is selected. Two different modes are available: on-line printing and batch
printing. Using the on-line mode, users can print (see Figure 8):
•
Screenshots: prints what is currently visible in the viewer;
•
On-screen parcels: prints a parcel based on its LPIS number, which is entered into the relevant field.
•
On-screen herd numbers: prints a farmer’s entire herd at a zoom level and paper size chosen by the user;
•
On-screen townlands: prints a townland map with any required background depending on user preference.
Spatial
query
panel
Figure 7. Spatial query panel: the user can enter query details such as the shape of the geometry, the distance from
specified map coordinates, the query type (window, buffer, etc.), the topological relations (overlap, touch, equal,
anyinteract, etc.). The corresponding automatically generated SQL statement can be viewed and manually edited if
required.
Print
panel
Figure 8. Printing panel with on-line option: a wide range of parameters can be selected by the user (zoom levels, paper
size, background settings, etc.).
4. Performance
In this section we provide some operational results of the Land Information Management System developed for the Irish
Department of Agriculture. This system (on-line since February 2002) serves 125,000 farmers in the territory of the
Republic of Ireland for a total of 700,000 field parcels. Table 1 shows typical dataset sizes in terms of number of bytes and
number of records.
Type of Dataset
Orthophotography
OS Maps in Raster Format
Geometries
Size of Datasets
80GB
180GB
12GB
No of Records
24,000
24,000
7,000,000
Table 1. Typical dataset sizes.
In the first two weeks of on-line operation the system generated 200,000 maps. The average number of spatial users is 16,
with a peak number of 64. The average response time for a locate query is 7 seconds without caching capabilities. Cached
locate queries require on average 2 seconds. Updates (e.g. posting a new geometry) require an average time of 5 seconds
including recalculation of topology within the database. Further testing of processing times under load is currently ongoing.
5. Conclusions
This paper presents an application of e-SpatialTM technology, an innovative software solution that extends Oracle Spatial
databases by adding spatial information management functionality that can be used within web-enabled applications
accessed via any device that supports the Java Virtual Machine (e.g., standard web browsers, PDAs and 3G mobile phones).
A major advantage of this technology is that it does not require the use of complex GIS proprietary application specific
software.
The use of the Oracle Spatial database environment allows for a unified way of handling both spatial and non-spatial data
within the same database. Typical GIS applications (e.g., ArcInfo, MapInfo, etc.) store the two types of data separately.
Besides reducing the complexity of system management by eliminating the hybrid architecture of typical GIS data models,
additional specific benefits (from the point of view of data management) of exploiting the Oracle Spatial unified approach
include:
•
The possibility for users to access full function spatial information systems based on industry standards with an
open interface to all data (e.g., SQL);
•
The capability of storing spatial data in enterprise-wide database management systems thereby enabling the
spatial development of several more enterprise applications;
•
The complete integration of management information and spatial data repositories that allows for web enabling
the development of geo-spatial applications providing additional analysis and reporting functionality.
From a data management point of view, a critical issue involves guaranteeing the preservation of topological consistency
(Egenhofer and Franzosa, 1991). The integrated Oracle 9i topology management functionality completely controls topology
within the iSMARTTM+iSIS platform: if a spatial element is updated, all spatially related elements are automatically
changed accordingly to guarantee consistency.
Using e-Spatial technology, no application code is ever installed on the client side, thereby eliminating any redundant code.
The thin client applet supports an unlimited number of users and an unlimited number of applications. With the database
generating all requested information (including both application functionality and attribute data) on the fly, only the
minimum data required is downloaded to the client, which leads to the most economical usage of bandwith and resources
for real-time response.
In this paper we have shown the potentialities and performance of e-SpatialTM technology as deployed in the land
information management system developed for the Irish Department of Agriculture. This system serves 125,000 farmers in
the territory of the Republic of Ireland and after two weeks of on-line operation, it generated 200,000 maps. This
application provides a seamless Oracle 9i Spatial database environment for the combination of multiple land information
datasets. The normal edit (e.g. create, modify, and delete) and spatial analysis functions associated with a traditional GIS
based land management applications, are deployed as Java stored procedures in the Oracle Spatial database. Integrated
database topology ensures the integrity of the topology relationships within the spatial database. The automatic
preservation of topological properties makes this system a reliable decision-making tool. Statistical data analysis (e.g.,
land use, land classification and land ownership changes over time, etc.) can also be easily compiled using standard Oracle
reporting functionality. Implementation and testing to make the land management information system available also on
hand-held mobile devices are currently under development.
In the past spatial information was utilised within specialised applications and exclusively by expert high-end users.
Recently, thanks to the diffusion of desktop GIS and the Internet, its integration within the widest range of applications is
becoming a common requirement. Therefore, a pressing need relates to providing non-expert users with easy-to-use
environments where they can visualise, query and manipulate spatial data without requiring any specific GIS,
programming, or database management background. To this purpose, additional tools to build and customise graphic user
interfaces that facilitate interaction with the iSMARTTM+iSIS platform have also been developed. Such tools provide a
user-friendly environment based on drag-and-drop functionality, without requiring any specific programming skills. In this
way, even non-expert users can easily build their own spatially enabled applications.
Finally, while existing systems are restricted to using all the data contained within each data layer with no ability to switch
on/off specific subsets of spatial data, e-SpatialTM allows users to select the particular data they wish to view and query.
This ability to switch on and off data and also define exactly what the users need to query greatly improves the speed with
which the individual query is completed. This characteristic also conforms to the information-on-demand approach
discussed by several authors in the context of web-based vector map generalization (Bertolotto and Egenhofer, 2001;
Buttenfield, 1999; Cecconi and Weibel, 2000). The potentialities of the application of e-SpatialTM technology in this context
are currently under investigation.
6. Acknowledgements
The authors wish to thank the Irish Department of Agriculture for their cooperation and input into the preparation of this
paper.
7. References
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